Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With annotations covering only read/destructive/openWorld, the description adds substantial behavior: the approval card shows the exact subject+message before send, there is a hard invite+one-reminder rate limit, and completion arrives asynchronously as a notification with draft-page counts (explicitly 'don't poll'). This is exactly the operational context annotations cannot express.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loads the core action and framing in the first clause, then layers operational constraints. It is a dense single paragraph and reads as slightly run-on, but nearly every clause carries distinct information, so almost nothing is wasted.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool that sends real outbound email through an approval flow with no output schema, the description covers the full lifecycle: message authoring, approval gating, rate limit, and async completion signal. Nothing an agent needs to invoke it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3, but the description adds content guidance for `message` beyond the schema — short, human, explains why THEIR knowledge matters, ~15 minutes, no account needed — which tells the agent what to actually write, not just where it goes.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Emails the guest link for an existing interview') and pins the framing ('from the REQUESTING USER'). The word 'existing' cleanly separates it from compass_interviews_create, so an agent can distinguish it from siblings without opening a schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives clear context: use it while framing a message in the requesting user's voice, respect the invite-plus-one-reminder limit, and expect a notification rather than polling. It never names a sibling alternative or an explicit when-not condition, which is the only thing keeping it below a 5.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.